The 'Lighter' Side Of The Force
The theory is very weak i would put Rey more in the realm as a reincarnated Anikin Skywalker / Darth Vader That has been brought back to make amends and bring balance to the force. This could be the cheating death that he was looking for in episode 3. There is a bunch of other things I could go into on this but i need sleep. Watch the film again with this Theory in mind and you will see its more than just possible but very exciting if they do decide to go down thats rout
NO, IT CAN'T BE TRUE, IT JUST CAN'T BE
I think it is as simple as the Dark Side is always gonna be a temptation to a Jedi, especially of the forces of the Dark Side have their eyes set on them so, ignoring the specifics paths proposed by this theory, it's not really saying anything more than what's expected. I also believe that despite the reuses of plot concepts from the original trilogies (which I believe are actually used with purpose on not simply to rehash but are also use to help restore the "feel" of the originals in this first new film), Disney will not allow their precious new franchise to lose favor with its target market by continuing to be repetitive in the future films despite viewer complaints (that was George Lucas' ego, not Disney's style).
Dark Side Rey > Light Side Rey